JP2001195795A - Motion controller device for magnetic tape as well as motor cleaning device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restore the reliability of a motor used in a tape drive. SOLUTION: This device has a first reel assembly having a first motor which rotates in a first direction in order to deliver a magnetic tape and rotates in a second direction in order to take up the tape and a second reel assembly having a second motor which rotates in the first direction in order to take up the magnetic tape delivered by the first reel assembly and rotates in the second direction to deliver the magnetic tape to the first reel assembly and is a device controlling the motion of the magnetic tape in the tape drive. The device described above has a means for starting a motor cleaning control unit in order to clean the interface of the commutator and brush of at least one motor of the first motor and second motor connected to a motor cleaning power source when the tape drive is inactive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to the field of repairing electric motors, and more particularly to direct current (DC).
The present invention relates to repairing an interface between a commutator and a brush of a motor without disassembling the motor.

[0002]

2. Description of the Related Art In certain applications using a direct current (DC) motor, the interface between the commutator and the brush making up the motor is interrupted by being soiled or covered by a coating commonly known as "varnish". Unintended and unreliable operation is caused to cause a change in speed resulting in unreliable rotation. In a data processing system tape drive, constant movement of the tape through the transducer is essential. Any impediment to constant speed will cause errors in reading or writing data from tape, thereby causing impairments in the data processing system. The rotation speed of the motor and thus the linear speed of the tape must not be varied. The reel-to-reel operation control system of the tape drive sets the DC tension on the tape using the calculated motor current. When the motor is driven at a low current for a long period of time, dirt adheres to the brush, and the reliability of connection with the commutator is reduced. This causes data errors and tape damage if the system attempts to run the tape and tries to maintain the proper tension between the two reels. Brush motors cannot operate with a low current through a brush for a long time in servo control applications such as magnetic tape drives. A high current density through the brush-commutator interface as well as the high speed is necessary to keep the interface clean and thereby maintain speed reliability. These things are not always available, especially in tape drives used in data processing systems. The tape becomes very thin, so that the tape drive requires significantly lower current to maintain tape tension between the reels. The current required for steady state operation will be lower once the tape has run, due to the lower energy required to maintain steady state operation. For most of the time, there is no self-cleaning action on the brush-commutator interface in the area where the motor is.

[0003] As a general method of cleaning the interface between the commutator and the brush of a motor, a Freon (trademark), a kind of chlorofluorocarbon compound, is sprayed and dried. The advantage of this cleaning method is that FREO
The rapid vaporization of N ™ eliminates any doubts about armature windings dipped after drying with this cleaning method. Operation of the motor with wet windings must be avoided. This may cause a short circuit in the winding. Due to uncertain drying methods and environmental incompatibilities due to the use of chlorofluorocarbons, this method is not particularly suitable for use in data processing systems.

[0004] Another common solution is to remove the tape drive and then remove and disassemble and clean the motor. In small data processing systems,
Removing the tape drive unit completely shuts down the operation of the data processing system and essentially shuts down its function. Large data processing systems at least affect productivity.

[0005]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a motor, In particular, a method is provided for restoring the reliability of a motor used in a tape drive.

It is a primary object of the present invention to provide an improved method and apparatus for cleaning the commutator-brush interface of a direct current (DC) motor.

[0007] A second object of the present invention is to provide a motor-driven unit in which the motor is mounted.
Another object is to provide a method and apparatus for cleaning the interface between the commutator and the brush while operating in the unit.

It is a third object of the present invention to provide a method and apparatus for cleaning the commutator-to-brush interface of a DC controlled speed motor useful for tape drives in data processing systems.

A fourth object of the present invention is to provide a method and apparatus for cleaning the interface between a commutator and a brush of a controllable motor, and to provide information indicating the result of the cleaning operation.

[0010]

SUMMARY OF THE INVENTION The present invention provides a method of cleaning the commutator-brush interface of a direct current (DC) motor, comprising the step of providing a relatively high current to the motor. The polarity of the current changes and is achieved at a variable duty cycle. The motor remains driven during the cleaning process. Neither the motor nor the units driven by the motor require disassembly.

In particular, a DC motor controlled at a constant speed has a commutator that is cleaned by applying a square wave alternating polarized direct current to the motor. Motors are particularly useful in tape drives for data processing systems or anywhere a speed controlled motor is desired. Square wave alternating polarized DC is preferably applied to a variable duty cycle to control motor heating. Cleaning is accomplished by baking off the coating on the commutator to restore intimate electrical contact between the commutator and the brush of the motor.

According to the present invention, the maximum amount of alternating polarized DC
A method and apparatus is used to clean the interface between the commutator and the brush of the DC motor by applying it to the motor. The method and apparatus of the present invention can be used and activated when the motor is inactive and the drive operated by the motor is idle. The goal of the cleaning cycle is to clean all of the commutator segments by allowing the motor to rotate in the opposite direction while providing high current. The high current flowing through the motor is obtained by reversing the direction of the applied voltage, and the resulting current does not substantially impart rotation to the motor. The apparatus of the present invention provides a motor cleaning device that applies a variable pulse width modulation motor cleaning power to a tape operation control unit and selectively applies an output of the motor cleaning power to the motor when the tape operation control unit is inactive. Has a control unit.

In a method of cleaning an interface between a commutator and a brush of a DC motor, the process includes connecting a cleaning power source to the motor. Preparing the cleaning power supply produces a pulsed square wave current of alternating polarity and adjustable frequency. Waveform and peak current times are selected based on motor wattage and mass. The current waveform is selected to provide either slow rotation or no net rotation of the motor. The tachometer signal from the tape motion control unit may be monitored to diagnose the cleanliness of the brush-commutator interface. The current can be varied to reverse the net rotation of the motor. The motor cleaning control unit can monitor the leaning process to monitor the output of the motor, thereby increasing the duty cycle asymmetry and creating diagnostic messages or longer cleaning of motor problems. • Initiate and control cycles.
In a tape drive unit having two reels, each motor may be cleaned separately or together, or monitored simultaneously. The cleaning process may be performed after each tape cartridge removal operation.

The present invention enables a method of cleaning a commutator of a motor with the motor mounted on a unit driven by the motor. The present invention allows for a cleaning method that is quick and easy without removing the unit or the motor itself. The cleaning method according to the invention can be carried out in the field where the unit is used, without having to remove the unit or the motor for the cleaning method at the factory. In addition to the other benefits from these improvements, these improvements provide significant cost savings benefits. For all of these reasons, it goes without saying that the present invention has significant inventive step and novelty compared to the prior art.

The above and other objects, features, and advantages of the present invention will be readily apparent to those skilled in the art by studying the embodiments of the invention described in detail below with reference to the accompanying drawings. The same reference numerals indicate the same components throughout.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The present invention is based on the fundamental problem that arises when using a large brush type motor and a steady current is not sufficient to keep the brush and commutator clean. Brush motors cannot operate with small currents through the brush for long periods of time, such as in servo control applications. Sufficient current density is required through the brush-commutator interface to keep the interface clean. There are numerous brush brands to address the problem of brush wear and the problem of maintaining good electrical contact with the commutator. The commutator of the motor becomes dirty by use. In systems where large motors are used to provide start and stop operations, the large current is not as large as required for operation to clean the brush-commutator interface. In many cases, the current required for operation between states is very small. In such a case, the motor operates in an area where self-cleaning of the brush-commutator interface, which would normally occur when no large current is applied, occurs. This is especially true for motors that use magnetic tape drives for data processing systems.

In current magnetic tape drive systems, large motors provide the quick start and stop operations required by data processing systems. As the magnetic tape itself is becoming thinner, the system requires a significantly lower current to maintain tape tension between the reels of the tape drive. Once the tape starts moving, the tape drive is a very low friction system and requires less energy to keep operation constant. for that reason,
Since no large current is used, a self-cleaning operation of the brush-commutator interface is not available.

In current data processing system tape drives, the tape control system relies on a motor to quickly output the required torque. The design uses a constant current driver with a digital-to-analog converter used by the control processor to command the required current. If the motor brushes do not make complete contact with the commutator due to fouling of the commutator segments, the tape tension is temporarily lost, which can damage the tape and lead to data loss. If the control loop cannot get the required torque from the motor because the commutator segments are dirty, there will be a temporary drop in tension or speed. The control loop responds to disturbances and continues to command higher torque without any effect on the motor. Eventually, the motor will rotate enough to bring another section of the commutator into contact with the brush,
The motor outputs the required torque. In this regard, the required torque is very high and the loop is overcorrected, resulting in a temporary rise in tension.
The event of excessive tension momentarily changes the tape from a loose state to a tight state at once, causing tape breakage. Accordingly, the present invention, which provides a method and apparatus for cleaning the brush-commutator interface of a DC motor, is particularly important when used in a data processing unit tape drive system. Accordingly, the detailed description of the preferred embodiment discusses a motor cleaning operation specifically used in tape drives of data processing systems.

The tape motion controls used herein are disclosed in US Pat. Nos. 4,125,881 and 4,050, assigned to the assignee of the present invention and incorporated herein by reference.
Includes specific methods used in the apparatus disclosed in US Pat. No. 15,799. Also incorporated by reference is assigned to the assignee of the present invention and issued on November 19, 1996.
No. 5,576,905 to Garcia et al. The preferred embodiment of the present invention is primarily directed to motors used in tape drives. The reason lies in the operation of the tape drive. However, the cleaning operation of the present invention can be used with any motor that uses a DC motor that can be quickly activated and quickly relocated and inverted during operation. The present invention is illustrated in FIG.
The tape drive shown in FIG.

The present invention can be understood with reference to FIG. In FIG. 1, the bidirectional reel-to-reel tape
The drive 10 has a pair of reels including a reel 11 driven by a motor 16 and a reel 17 driven by a motor 21. Fine wire tachometers 12 and 18 are provided on the drive shafts of the motors 16 and 21, respectively. In addition, a plurality of fine wires 14 and 19 and an index line 15 which extend radially from the periphery of the fine wire tachometers 12 and 18 toward the inner coating wheel and an index line 15
A plurality of 0s are formed to provide a thin line array. The tape 22 is wound over the reel 11 and the reel 17, and the motors 16 and 21 control the movement of the tape in one of two directions indicated by an arrow 23 for recording or rewinding.

Each of the tachometers 12 and 18 functions as a tape motion sensor. Each of the tachometers 12 and 18 emits a single pulse in response to the index line,
A relatively large preselected angle, preferably 300
Degrees, ie once per revolution of reels 11 and 17,
The operation of the tape is indicated by issuing a pulse. Also, each of the tachometers 12 and 18 produces a two-phase fine wire tachometer signal that includes a two-phase display pulse stream. The tachometer thin line arrangement on tachometers 12 and 18 is identical,
Each of the reels 11 and 17 emits an impulse according to the rotation of the corresponding reel.

While advancing the tape 22, while recording data on the tape 22, various parameters, such as tape, are used to derive a motor current having the polarity and magnitude necessary to operate the motors 16 and 21. Movement, position and tension are monitored. Such current is induced in response to the tachometer wire and tachometer index signals to the tape motion control unit 26 by the algorithm of the incorporated US Pat. No. 4,125,881 signal. The tape operation control unit 26 has a tachometer thin line and an index line pulse, and each current line 2
Current is passed to motors 16 and 21 on 7 and 28. The signals on current lines 27 and 28 are coupled to amplifiers 29 and 30
Are amplified respectively. The amplified motor current is transmitted to the motors 16 and 21 via the output lines 32 and 33 of the amplifiers 29 and 30.

The tape motion control unit 26 operates the motors 16 and 21 to maintain a constant nominal speed for recording, reading, and searching. Other portions of the tape drive 10 shown in FIG. 1 are disclosed in U.S. Pat.
It can be maintained as described in 5,576,905. The tachometer assembly shown in U.S. Pat. No. 5,576,905 has a conventional optical sensor / encoder that produces a stream of tachometer pulses in response to rotation of a code wheel,
An index pulse is generated once for each revolution of the code wheel.

Referring again to FIG. Reference numeral 101 indicates a motor cleaning system according to the present invention. The system 101 includes a power supply 103 and a control unit 1
05. The current is sent directly from the power supply 103 to the control unit 105 and further distributed to the motors 16 and 21 via output lines 32 and 33. Control unit 1
05 is activated by a signal called the clean motor signal, shaved on line 107. The clean motor signal is supplied to the recording channel control unit 35 as shown in FIG.
Or by any other control unit. The present invention uses a method and apparatus for cleaning a motor that aims to deliver the maximum amount of current to the brush-commutator interface in the shortest amount of time. The solution is to use a method of cleaning the motor with no tape drive cartridge loaded and while the drive is idle. The purpose of the cleaning cycle is to apply a large current to the motor and slowly rotate the motor to clean all commutator segments.

Rotating the motor to clean the brush-commutator interface is not effective for this particular problem in that the motor is used in a tape drive. The motor of the tape drive is driven by a constant current driver. If the control processor sets the value of the DAC register of the tape motion control unit 26, the control loop through amplifiers 29 and 30 will attempt to quickly deliver the required current. If a large current is required, the motor is accelerated so quickly that increasing the speed of the motor increases the back EMF in proportion to the rotational speed of the motor. This sharply reduces the current flowing through the motor as the speed of the motor is maximized. At the maximum no-load speed of the motor, the back EMF is very high and the current through the motor is very low. High currents flowing through the motor, which may be useful for the cleaning method, can only be achieved with acceleration or deceleration, where the motor back EMF does not oppose the voltage applied to the motor. It is only the stop process that the back electromotive force of the motor does not go against the applied voltage. In order to obtain the maximum current flowing through the motor, it is required to start or stop the motor by reversing the direction of the current applied and the voltage applied to the motor without substantially rotating the motor. The present invention utilizes the majority of the motor by initiating rotation of the motor and subsequently reversing the polarity of the applied current by rotating the motor in the opposite direction. In one embodiment, shown in FIG. 2, an attempt is made to pass a peak DC current of 4 amps to the motor.

As shown in FIG. 2, if a 50% duty cycle voltage waveform is applied to the motor, the motor starts to rotate in one direction and only stops and the polarity of the voltage is reversed. Rotate in the opposite direction. Therefore,
During time T1, the motor attempts to rotate in one direction when a peak current 110 is applied,
When 2 is applied, an attempt is made to rotate in the other direction. The progressively alternating currents, for example, currents 114, 116, 118 and 120 peaks, are directed to the motor to start and stop the motor, and then the reverse direction as the applied voltage and the resulting current are directed to the motor. The motor starts. In order to obtain the maximum current flowing through the motor, it is desirable to start and stop the motor by reversing the direction of the applied voltage and the resulting current through the motor without rotating the motor at all. Most of the motor is used by reversing the polarity of the applied voltage, as the motor starts rotating and the motor rotates in the opposite direction as shown in FIG. The motor starts rotating in one direction only to stop, and rotates in the opposite direction when the current reverses. This will result in a motor that is noisy without any net rotation of the commutator. If the duty cycle is short enough, the motor will get the maximum current per unit time through the brush. The wavelength cycle is selected based on the available current and the size of the motor and can be easily determined experimentally. Once the motor starts rotating, the back EMF determines the current flowing through the motor. It is shown in FIG. 2 that a current of the order of 4 amps is sufficient to perform a cleaning operation on the brush-commutator interface. Further, it is desired to rotate the motor so that all sections of the commutator are cleaned, and a method for accomplishing this is shown in FIG.

As shown in FIG. 3, the motor hums by changing the demand current from the 50% duty cycle so that the net current in one direction is greater than the other. It can rotate slowly in the direction of the higher net current. As shown in FIG. 3, the positive current pulses 122, 124, and 126 are:
Includes longer times T1, T2, and T3. Also,
The motor drives the applied negative current pulses 123, 125,
And 127. The deviation of the duty cycle in FIG. 3 from the 50% duty cycle can be used to reduce motor rotation and diagnose motor problems. In the particular embodiment disclosed in FIG. 3, the 10 ms vs. 12 ms duration is the starting point of the current difference. Thus, the positive peaks 122, 124, and 126 are held for a time of 12 milliseconds, while the negative current pulses 123, 125, and 127 are held for a time of 10 milliseconds. These time intervals were used as starting points for the current difference. In the system shown in FIG. 1, each motor has a fine wire tachometer 12 or 18 which is connected to motors 16 and 21, respectively.
Direction and velocity information can be obtained using a rectangular signal as disclosed in US Pat. No. 5,576,905. By monitoring the signal of the tachometer, it is confirmed whether the rotation of the motor is in the expected direction and at the desired net rotation speed. If there is a bad spot on the commutator, the motor will stall at low speed and noise will reappear at this spot, even if there is a net current in one direction. The dirty commutator section provides a directional bias in the system that substantially cancels the offset from the 50% duty cycle as shown in FIG. 3, thereby causing a difference in the net current through the motor being cleaned. Occurs. The ability to diagnose a problem during a cleaning cycle, and to use this diagnostic anyway, continues cleaning by altering the net current offset. This information can also be used to recognize if the motor is in a bad state or does not require cleaning. For example, the control system of the recording channel control 35 monitors the rotation of the motor,
Increase the duty cycle asymmetry and rotate the motor again accurately. This invokes a diagnostic message indicating a longer cleaning cycle or a problem with the motor. In the preferred embodiment, at the end of 4 seconds, the motor is stopped and the overall operation is as shown in FIG.
Is repeated in the reverse direction as shown in FIG.

As shown in FIG. 4, the duty cycle is reversed to produce a net current in the opposite direction. As shown in FIG. 4, positive current application pulses 128, 130, and 13
2 is smaller than the negative current application pulses 129, 131, and 133. The motor rotates slowly in the opposite direction, while humming, as shown in FIG. A net current occurs in the opposite direction. Monitor motor rotation and readjust the duty cycle if a bad or dirty spot is on the commutator. After 4 seconds of cleaning in each direction, the cleaning operation is terminated if no problem is detected, for example using the pulse of FIG. 3 or FIG. The cleaning operation of the preferred embodiment is performed on each and every cartridge removal operation. It should be noted that the cleaning operation is performed on a single motor at a time.
In a preferred embodiment, the control algorithm
However, generally, cleaning is performed simultaneously, and both motors are independently controlled. The cleaning is performed individually, but since both motors have the same interface between the brush and the commutator, cleaning is generally performed simultaneously.

Although the present invention has been illustrated and described based on the preferred embodiments, the spirit, scope, and
Those skilled in the art will readily appreciate that various changes can be made in form and detail without departing from the teachings. For example, in FIG. 1, the motor cleaning system 101 and its control unit 105 are controlled by a clean motor pulse from the recording channel control 35. The control unit 105 can be activated by a number of other means, such as by manually controlling the start of a cleaning operation. In this regard, it is clear that the separation system controls operations such as inserting and removing cartridges from the tape drive system. It is also clear that motors other than those of the tape system have similar problems and situations as those already described. Therefore, the above detailed description is considered merely illustrative, and the invention is limited only by the claims.

In summary, the following matters are disclosed regarding the configuration of the present invention. (1) a first reel assembly having a first motor that rotates in a first direction to unwind a magnetic tape and rotates in a second direction to wind the magnetic tape; Rotating in a first direction to wind the magnetic tape unreeled by the reel assembly of
And a second reel assembly having a second motor that rotates in a second direction for feeding the magnetic tape to the first reel assembly, the apparatus controlling movement of the magnetic tape in the tape drive. A motor cleaning power supply for generating an alternating polarity, an adjustable current, and a variable frequency square wave; and selectively outputting current from the motor cleaning power supply to the first motor and the second motor. A motor cleaning control unit connected to supply and at least one of the first motor and the second motor connected to the motor cleaning power supply when the tape drive is otherwise inactive. The motor cleaning system is used to clean the interface between the commutator and the brush of the motor. Operation control device of the magnetic tape, characterized in that it comprises a means for activating the unit. (2) the motor cleaning power supply generates a control pulse width modulated current in a cleaning cycle and does not cause a net rotation of the motor or causes a net rotation of the motor in any direction. The operation control device for a magnetic tape according to the above (1). (3) The motor cleaning power supply as described in (2) above, wherein the motor cleaning power supply generates a pulse current of 4 amps with a 50% duty cycle and does not cause a net rotation of the motor throughout the cleaning cycle. Operation control device for magnetic tape. (4) The motor being cleaned and the fine wire tachometer of the motor are sensed and monitored to ensure that the motor being cleaned is rotating in the expected direction at the desired net rotational speed. The operation control device for a magnetic tape according to the above (1), wherein the operation control device confirms the operation. (5) The magnetic tape operation control device according to (4), wherein the first motor and the second motor are simultaneously cleaned. (6) The operation control of the magnetic tape according to (4), wherein the fine wire tachometer is sensed during the cleaning cycle to determine whether the motor is defective. apparatus. (7) the fine wire tachometer is sensed during the cleaning cycle to determine whether the cleaning cycle should be completed or extended for more cleaning. The operation control device for a magnetic tape according to the above (4). (8) The motor cleaning power supply generates a control pulse width modulated current in the cleaning cycle, with each cleaning cycle having a longer period to cause a net rotation of the motor in one direction. The operation control device for a magnetic tape according to the above (1), wherein a positive pulse is applied to the magnetic tape. (9) The motor cleaning power supply generates a control pulse width modulation current in the cleaning cycle, wherein each cleaning cycle has a longer period to produce a net rotation of the motor in the other direction. The operation control device for a magnetic tape according to the above (1), wherein a negative pulse is applied to perform the operation. (10) The motor cleaning power supply generates a control pulse width modulated current in the cleaning cycle, with each cleaning cycle having a longer period to cause a net rotation of the motor in one direction. To
Wherein a positive pulse is applied followed by a negative pulse to make each cleaning cycle longer to produce a net rotation of the motor in the other direction. The operation control device for a magnetic tape according to (1). (11) A motor cleaning device for cleaning an interface between a commutator and a brush of a DC motor without disassembling the DC motor, wherein the motor generates an alternating polarity, an adjustable current, and a variable frequency square wave. A cleaning power supply, a motor cleaning control unit connected to selectively supply an output current from the motor cleaning power supply to the first motor and the second motor, and the tape drive comprises: Otherwise, the motor cleaning control is used to clean an interface between a commutator and a brush of at least one of the first motor and the second motor connected to the motor cleaning power supply when the motor becomes inactive. Means for activating the unit. Motor cleaning device. (12) The motor cleaning apparatus according to (11), wherein the motor cleaning power supply generates a control pulse width modulation current in a cleaning cycle and does not cause a net rotation of the motor. (13) The motor according to (11), wherein the motor cleaning power supply generates a control pulse width modulation current in a cleaning cycle to cause a net rotation of the motor in one of the directions.・ Cleaning device. (14) The motor cleaning power supply generates a control pulse width modulated current in the cleaning cycle, with each cleaning cycle having a longer period to cause a net rotation of the motor in one direction. To
(11) wherein a positive pulse is applied.
A motor cleaning device according to claim 1. (15) The motor cleaning power supply generates a control pulse width modulated current in the cleaning cycle, wherein each cleaning cycle has a longer period to produce a net rotation of the motor in the other direction. The motor cleaning device according to the above (11), wherein a negative pulse is applied to perform the cleaning. (16) The motor cleaning power supply generates a control pulse width modulated current in the cleaning cycle, with each cleaning cycle having a longer period to cause a net rotation of the motor in one direction. To
Wherein a positive pulse is applied followed by a negative pulse to make each cleaning cycle longer to produce a net rotation of the motor in the other direction. The motor cleaning device according to (11). (17) A method of cleaning an interface between a commutator and a brush of a DC motor without disassembling the DC motor, the method comprising generating an alternating polarity, an adjustable current, and a current having a variable frequency square wave. Cleaning the interface between the commutator and the brush of the DC motor by applying the current to the DC motor. (18) The step of generating the current includes generating a control pulse width modulated current in a cleaning cycle, wherein each cleaning cycle is performed with a longer cycle to produce a net rotation of the motor in one direction. The cleaning method according to the above (17), wherein a positive pulse is applied to perform the cleaning. (19) The step of generating the current includes generating a control pulse width modulation current in a cleaning cycle, wherein each cleaning cycle is performed with a longer cycle to cause a net rotation of the motor in the other direction. The cleaning method according to the above (17), wherein a negative pulse is applied to perform the cleaning. (20) The step of generating a current comprises generating a control pulse width modulated current in a cleaning cycle, wherein each cleaning cycle is performed with a longer period to produce a net rotation of the motor in one direction. A positive pulse is applied, and then a negative pulse is applied to make each cleaning cycle longer so as to cause a net rotation of the motor in the other direction. The cleaning method according to the above (17), which is characterized in that:

[Brief description of the drawings]

FIG. 1 shows a tape with a tape operation control unit having a motor cleaning unit according to the invention.
FIG. 3 is a schematic circuit diagram for explaining a drive.

FIG. 2 is a waveform diagram illustrating a waveform generated by the motor cleaning unit of FIG. 1 in accordance with the present invention and illustrating a duty cycle in which the motor exhibits little net rotation;

FIG. 3 is a waveform diagram illustrating a waveform generated by the motor cleaning unit of FIG. 1 according to the present invention and illustrating a duty cycle in which a net rotation of the motor is recognized in only one direction.

FIG. 4 shows a waveform generated by the motor cleaning unit of FIG. 1 in accordance with the present invention, wherein the duty cycle is such that a net rotation of the motor is observed only in the opposite direction.
FIG. 4 is a waveform diagram for explaining a cycle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Tape drive 11, 17 reel 12, 18 Fine wire tachometer 14, 19 Fine wire 15, 20 Index line 16, 21 Motor 17 Reel 26 Tape operation control unit 27, 28 Current line 29, 30 Amplifier 32, 33 Output line 35 Recording channel control unit 101 Motor cleaning system 102 line 103 Power supply 105 Control unit 110 Peak current 114, 116, 120 Current 122, 124, 126 Positive current pulse 123, 125, 127 Negative current pulse 128, 130, 132 Positive Current application pulse 129, 131, 133 Negative current application pulse

Claims (20)

[Claims] A first motor having a first motor that rotates in a first direction to unwind the magnetic tape and rotates in a second direction to wind the magnetic tape; A second motor that rotates in a first direction to wind the magnetic tape unwound by the first reel assembly, and that rotates in a second direction to unwind the magnetic tape onto the first reel assembly; An apparatus for controlling movement of a magnetic tape in a tape drive, the motor cleaning power supply generating an alternating polarity, an adjustable current, and a variable frequency square wave; and Motor cleaning control connected to selectively supply output current from the motor cleaning power supply to the first motor and the second motor Cleaning an interface between a brush and a commutator and a brush of at least one of the first motor and the second motor connected to the motor cleaning power supply when the tape drive is otherwise inactive. And a means for activating the motor cleaning control unit. 2. The motor cleaning power supply generates a control pulse width modulated current in a cleaning cycle to cause no net rotation of the motor or cause net rotation of the motor in any direction. The operation control device for a magnetic tape according to claim 1, wherein: 3. The motor cleaning power supply of claim 2 wherein said motor cleaning power supply produces a 4 amp pulse current at a 50% duty cycle and does not cause a net rotation of said motor throughout said cleaning cycle. Operation control device for magnetic tape. 4. The motor being cleaned and a fine wire tachometer of the motor being sensed and monitored,
2. The magnetic tape operation control device according to claim 1, wherein it is confirmed that the motor being cleaned is rotating in a predicted direction at a desired net rotational speed. 5. An apparatus according to claim 4, wherein said first motor and said second motor are simultaneously cleaned. 6. The cleaning apparatus according to claim 1, wherein the fine wire tachometer is configured to determine whether the motor is defective.
5. The apparatus according to claim 4, wherein the operation is detected during a cycle. 7. A fine wire tachometer for determining whether the cleaning cycle is to be terminated or extended for further cleaning.
5. The apparatus according to claim 4, wherein the operation is detected during the cleaning cycle. 8. The motor cleaning power supply generates a control pulse width modulated current in the cleaning cycle, with each cleaning cycle having a longer period to produce a net rotation of the motor in one direction. 2. The magnetic tape operation control device according to claim 1, wherein a positive pulse is applied to perform the operation. 9. The motor cleaning power supply generates a control pulse width modulated current in the cleaning cycle, wherein each cleaning cycle is extended to produce a net rotation of the motor in the other direction. 2. The magnetic tape operation control device according to claim 1, wherein a negative pulse is applied to set the period. 10. The motor cleaning power supply generates a control pulse width modulated current in the cleaning cycle, with each cleaning cycle having a longer period to produce a net rotation of the motor in one direction. A positive pulse is applied to each of the cleaning stations, followed by each cleaning cycle to cause a net rotation of the motor in the other direction.
2. The magnetic tape operation control device according to claim 1, wherein a negative pulse is applied to make the cycle longer. 11. A motor cleaning device for cleaning an interface between a commutator and a brush of a DC motor without disassembling the DC motor, wherein the motor cleaning device generates an alternating polarity, an adjustable current, and a variable frequency square wave. A motor cleaning power supply, a motor cleaning control unit connected to selectively supply an output current from the motor cleaning power supply to the first motor and the second motor, and the tape drive. The motor motor to clean the commutator-brush interface of at least one of the first and second motors connected to the motor cleaning power supply when otherwise inactive. Means for activating the cleaning control unit; and Characterized motor cleaning device. 12. The motor cleaning apparatus according to claim 11, wherein said motor cleaning power supply generates a control pulse width modulation current in a cleaning cycle and does not cause a net rotation of said motor. 13. The motor cleaning power supply of claim 11, wherein said motor cleaning power supply generates a control pulse width modulated current in a cleaning cycle to cause a net rotation of said motor in either direction. Motor cleaning device. 14. The motor cleaning power supply generates a control pulse width modulated current in the cleaning cycle, with each cleaning cycle having a longer period to produce a net rotation of the motor in one direction. 12. The motor cleaning apparatus according to claim 11, wherein a positive pulse is applied to perform the cleaning. 15. The motor cleaning power supply for generating a control pulse width modulated current in the cleaning cycle, wherein each cleaning cycle is extended to produce a net rotation of the motor in the other direction. 12. The motor cleaning apparatus according to claim 11, wherein a negative pulse is applied to set a period. 16. The motor cleaning power supply generates a control pulse width modulated current in the cleaning cycle, with each cleaning cycle having a longer period to produce a net rotation of the motor in one direction. A positive pulse is applied to each of the cleaning stations, followed by each cleaning cycle to cause a net rotation of the motor in the other direction.
The motor according to claim 11, wherein a negative pulse is applied to make the cycle longer.
Cleaning device. 17. A method for cleaning an interface between a commutator and a brush of a DC motor without disassembling the DC motor, the method comprising generating an alternating polarity, an adjustable current, and a current having a variable frequency square wave. Cleaning the interface between the commutator and the brush of the DC motor by applying the current to the DC motor. 18. The method according to claim 17, wherein the step of generating a current comprises generating a control pulse width modulated current in a cleaning cycle, wherein each cleaning cycle is extended to produce a net rotation of the motor in one direction. 18. The cleaning method according to claim 17, wherein a positive pulse is applied to set a period. 19. The step of generating a current includes generating a control pulse width modulated current in a cleaning cycle, wherein each cleaning cycle is extended to produce a net rotation of the motor in the other direction. 18. The cleaning method according to claim 17, wherein a negative pulse is applied to set a period. 20. The method of claim 19, wherein the step of generating a current includes generating a control pulse width modulated current in a cleaning cycle, wherein each cleaning cycle is extended to produce a net rotation of the motor in one direction. A positive pulse is applied to make the cycle, followed by each cleaning cycle to produce a net rotation of the motor in the other direction.
18. The cleaning method according to claim 17, wherein a negative pulse is applied to make the cycle longer.